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Subject: Re: task_struct.mm == NULL
From: Shaya Potter <spotter@cs.columbia.edu>
To: Linux Kernel List <linux-kernel@vger.kernel.org>
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Date: 28 Nov 2001 09:10:30 -0500
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On Wed, 2001-11-28 at 07:23, Andi Kleen wrote:
> Frank Cornelis <Frank.Cornelis@rug.ac.be> writes:
> 
> > Hey,
> > 
> > I found in some code checks for task_struct.mm being NULL.
> > When can task_struct.mm of a process be NULL except right before the
> > process-kill?
> 
> For kernel threads that run in lazy-mm mode. It allows a much cheaper context
> switch into kernel threads.

oh. so not all kernel threades have mm == null.  I used to think that
kernel threads ran in the kernel's address space, therefore there was no
point in having an mm struct as that just defines a virtual process
address space.  What's this lazy_mm mode?

thanks,

shaya

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